Abstract Pacific Islanders are an indigenous/colonized U.S. racial group that carries very high risk for opioid use disorders (OUD) due to their many social, economic, and health disparities and heavy burden of mental health and substance use disorders. Unfortunately, Pacific Islanders rarely seek OUD treatment for reasons that remain unexplored and unknown, resulting in high levels of unmet treatment need that increases Pacific Islanders? likelihood for experiencing opioid-related harms such as overdose and death. Despite their urgent need for OUD treatment, Pacific Islanders remain absent from current opioid research and do not seek formal treatment services during this severe public health crisis. The proposed R34 study will address this research and clinical gap by applying multifaceted methods to develop and pilot test the first intervention components designed to prevent untreated OUDs by increasing Pacific Islander OUD treatment seeking. Drawing from this team?s earlier behavioral health research with Pacific Islanders, we will use a culturally tailored intervention development approach that includes constructivist grounded theory, focus groups, and a deliberative public decision-making process called citizens? panels to engage lay Pacific Islanders in culturally grounding existing evidence-based practices to increase Pacific Islander OUD treatment seeking. By combining this collected information with feedback from a council of Pacific Islander experts and a Cochrane-style systematic review of the literature on OUD, substance use, and mental health treatment- seeking interventions, we will create a conceptual model containing culturally grounded components for the first OUD treatment-seeking intervention for Pacific Islanders. Simultaneously, we will create a set of questions to measure the effects of these intervention components. The intervention components and our measurement questions will then be pilot tested with a small group of lay Pacific Islander adults for feasibility, acceptability, and perceived efficacy in preparation for a future efficacy trial. Research findings will be disseminated back to our participants and target communities, community partners (organizations and clinics), and the scientific community via brochures, technical reports, community forums, and academic presentations and papers.